Please insert two values and leave the third blank.
Decimal digits: Calculate

Examples from astronomy: the moon has a size of approximately 3500 km (g) and a distance of 400000 km (r). It has an apparent size of about 0.5 degrees (α). The galaxy M51 is about 31 megalight-years away from us and has an angular diameter of 0.19 degrees, which corresponds to 103000 light-years diameter.At distances above hundreds of millions of light-years, the curvature of space plays a role, which is neglected here.

Example for a parallax: a mountain in a distance of 50 km, seen from two points 100 m away from each other (line between the points upright to the distance), changes its apparant position for 0.115°.